It means k per 9, meaning strikeouts per 9 innings pitched. It is a decent indicator for prospects (if you consider in their k/bb), and other pitchers. most pitchers with a high k/9 and a low k/bb will have already been picked. Of course, then you could look at OBA, P/I, P/G, GS, RS, (etc.) lol

98% of Americans have a favorable opinion of puppies and rainbows.
How do you spell "biased?"